The report published on Friday by the UN's intergovernmental panel on climate change (IPCC) is the second of three volumes that will together make up the group's fourth assessment report on the state of the planet.

Over more than 1,500 pages, scientists analyse what impact climate change will have on wildlife, habitats and communities around the world and what can be done to reduce the problems and threats faced by different countries.

Who has written it?The report is the work of hundreds of scientists who have reviewed scientific, environmental and socio-economic papers on the impacts of climate change. The scientists form the IPCC's second working group, which has been chaired by Professor Martin Parry of the Met Office and Osvaldo Canziani.

Their work has been commented on and added to by the representatives of more than 100 governments around the world. The wording of the completed report, and a 21-page summary for policymakers, is being approved this week at a conference in Brussels.

What will it say?The report is expected to warn that a scarcity of water, food and land brought about by climate change could lead to tension between nations and even war. Millions of people around the world will be affected by drought or flooding, with many forced to leave their homes in search of water, or find safer places to live away from rising sea levels.

It is expected to say that rising temperatures predicted in the IPCC's last report will lead to more hunger in Africa and more heatwaves in the US. The heat could melt glaciers in the Himalayas and further damage Australia's Great Barrier Reef.

Agriculture may be affected around the world, with many countries seeing a reduction in the amount of food they can produce, although some such as Canada and Russia may initially be more productive as their climate warms.

The outlook for wildlife is ominous, according to Reuters, which says a draft version of the report warns that 20-30% of species are likely to be at risk of extinction if the global average temperature rises by 1.5-2.5C.

What happens next?Next week the IPCC will hold regional briefings around the world to explain the observed and predicted impacts of climate change on each region.

The IPCC will publish one more paper before its fourth assessment report on November 16. The Mitigation of Climate Change report will be released on May 4 in Bangkok, then details from it and the other two reports will be brought together in the Synthesis Report.

The IPPC says this final report will pay more attention to the integration of climate change with sustainable development than its last assessment report, published in 2001. It will also focus more on the relationships between mitigation of the threat of climate change and adaptation to the problems it could cause.